The Canine and feline kidneys have many important functions. Among them are: to filter metabolic waste such as urea, mineral salts, and various toxins from circulating blood; to help regulate the volume of body fluids and the blood levels of important chemicals and hormones; to initiate the recirculation of purified blood throughout an animal’s system; and to facilitate the excretion of the filtered-out waste products (mixed with water to form urine) before they reach toxic concentrations in the body. Most cats and dogs will go through life without experiencing a serious disruption in these vital processes. Some others, however, will experience urolithiasis—a potentially lethal condition marked by the formation of small stones (uroliths) somewhere within this elaborate system.
The upper tract consists of two kidneys, which handle the biochemical processes; and two slender tubes (ureters)—one leading from each kidney—that deliver waste-containing urine from the kidneys down to the lower tract. The lower tract, whose function is purely excretory, consists of the bladder, a muscular sac that receives the urine delivered to it through the ureters and stores it until it is expelled from the body via the other component of the lower tract, the urethra, a thin tube leading from the bladder to the outside world. Stones can develop anywhere within either the upper or lower tracts of the urinary system.
Bladder stones are composed of minerals—either struvite or calcium oxalate—while kidney stones are always made of calcium oxalate. “These minerals are present naturally in a cat’s and dog’s body, the stones form when the minerals exceed a certain threshold of concentration in the urinary system. When the concentration goes over that threshold, they start to form crystals, and the crystals accumulate and may grow into stones. We don’t know why this process takes place, but we’ve observed that it tends to occur frequently in domesticated cats and dogs.
In some cases, bladder stones may be tiny and inconsequential, remaining harmlessly lodged somewhere within the urinary tract or passed without notice in a urine. In other cases, however, they can grow to significant size, painfully irritate the tender tissue lining the tract, and cause internal bleeding. In the worst case, they can slip into a urethra and interfere with the passage of urine. A complete blockage—one that totally obstructs the flow of urine and prevents the elimination of poisonous waste from a cat’s system—will present a medical emergency that, without immediate veterinary care, may prove fatal. Blockages are most common in male cats and dogs since they have a very narrow and easily obstructed urethra. Typical early signs include blood in the urine as well as increasingly frequent and painful urination.
Kidney stones, on the other hand, do not typically cause noticeable signs of disease until they become very large. Most of those go undiagnosed until there is a problem, Both kidney stones and bladder stones can be readily diagnosed by means of x-rays and ultrasound.
Regarding the treatment of kidney stones, In most cases, we don’t believe that we should go in, open the kidneys, and remove the stones unless they’re causing significant obstruction or infection. But bladder stones are typically treated either surgically or by managing the diet .
To reduce the risk of kidney and bladder stones, Make sure that your cat and dog always has access to water and is drinking it. they prefer fresh water, so don’t let it stand around for days.